Exhaust system for kitchens

ABSTRACT

An exhaust device (100) for a kitchen exhaust system incorporating a range hood (11) is disclosed, which is capable of substantially reducing generation of noise while efficiently evacuating fumes from the kitchen without a suction loss. The exhaust device (100) comprises a vent box (20) communicating with an exhaust duct (40), which may be housed in the hood (11) or in a housing box (10) provided above the hood (11). The vent box (20) includes a connection enclosure (20a) in its upper portion, which converges toward the duct (40). The vent box (20) contains a pair of partitions (21) each having a tilted plate (22), which provide a pair of vent routes (23). Between the partitions (21) is provided a drive motor (31) and in each vent route (23) is provided a sirocco fan (33) driven by the motor (31) whose blades (33a) are converged toward the motor (31).

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention generally relates to an exhaust system. This inventionmore particularly relates to an exhaust device to expel fumes from akitchen.

2. Prior Art

Fumes including oil particles, smoke, odor and steam as well as harmfulgaseous substances are unavoidably produced in a kitchen from cookingand imperfect combustion of cooking gas. Such fumes should beimmediately expelled from the kitchen to keep the air in the kitchenalways clean. Otherwise, the fumes will adversely affect not only peopleworking in the kitchen but also the gas combustion of the cookingutensil. Such fumes will also stain the kitchen walls. Japanese PatentLaid-Open Publication No. 3-274325 discloses a ventilation fan thatdirectly sucks and exhausts fumed kitchen air. It is also widelypracticed to arrange a range hood over a gas table or range to directlysuck up and exhaust fumes through an exhaust pipe or duct with the helpof a blower.

Naturally, an exhaust system with a range hood can more effectively suckand evacuate fumed kitchen air than a ventilation fan or fans. For thisreason, a range hood is often utilized for a so-called "system kitchen."It is true that the nearer a range hood is to a gas range, the moreeffective the exhaustion of fumed air from a kitchen will be.

However, the use of range hoods is not without a problem; there exists amajor drawback in a conventional range hood system, i.e. unpleasantnoise is generated during the operation of the system. This drawback ismainly due to the relatively limited dimension of an exhaust ductopening. A range hood is generally provided with a large opening tosufficiently cover a cooking range in order to collect most, if not all,fumed air directly therefrom, while an exhaust duct connected to therange hood is generally provided with a limited dimension which is muchsmaller than that of the range hood opening since exhaust ducts ingeneral must be installed through walls and above ceilings. Exhaustducts often have a dimension as small as 15 cm across. Exhaust ducts arealso destined to be bent at a number of places on their way to the exitopenings. Therefore, a powerful blower must be employed to forciblyexpel fumes through such a narrow and bent duct, which will naturallygenerate much unpleasant noise. Noises are also generated when the fumedair running in an exhaust duct hits corner walls of the duct.

Any obstructive factor or element in the ventilation route of a rangehood system not only deteriorates the expellant efficiency but alsogenerates noises. Considering the fact that an exhaust duct is made muchnarrower than the opening of a range hood, through which fumes areexpelled from a kitchen into the open air, there has been felt a demandfor an exhaust device that can powerfully suck fumes into a range hoodand into an exhaust duct to expel same into the open air with a muchreduced noise level.

Some kitchens are furnished with a fresh air supply system in additionto an exhaust system to cooperatively provide an improved exhaustion offumes. For such a kitchen, an exhaust system with a capacity "400 cubicmeter/h" will sufficiently do the work to exhaust much of fumed air,however, an exhaust system with a capacity "500 cubic meter/h" or sowill be required even with such a kitchen to also expel most of oilcontaining smoke from the kitchen. Without such a fresh air supplysystem, a kitchen will need an exhaust system having a capacity aspowerful as "700 cubic meter/h, max." to exhaust substantially all fumedair containing oil particles and smoke. Such a powerful system does notmatch a small duct having a dimension of only about 15 cm across. Ifinstalled, such a powerful system will generate very unpleasant noise.

So-called "sirocco fans" may be employed in an appropriate way to reducethe noise level, however, a sirocco fan including its casing generallycomes in a rather large overall dimension, demanding a substantialchange in designing of the whole kitchen system including the design ofits range hood, which is usually not feasible without major modificationto the sirocco fan itself when the limited space of a kitchen isconsidered.

The inventor of the present invention has made efforts to find a way toeffectively and substantially eliminate such noises from a kitchenexhaust system which incorporates a range hood, and has finally arrivedat the present invention.

SUMMARY OF THE INVENTION

An exhaust system of the present invention which provides an excellentsolution to the foregoing drawbacks of conventional exhaust systemsincludes an exhaust device 100 which forcibly draws fumed air producedfrom cooking on a kitchen range 210 into a range hood 11 and expels sameinto an exhaust duct 40, the exhaust device 100 including: a vent box 20which is installed either directly in the range hood 11 or in a housingbox 10 disposed additively over the range hood 11 in fluid communicationwith the exhaust duct 40; and a drawer device 30 housed in the vent box20, the vent box 20 including a connection enclosure 20a in its topportion, which opens to and converges toward the exhaust duct 40,further, a pair of generally vertical partitions 21 are arranged in thevent box 20, generally on the left and right of the longitudinal axis ofthe exhaust device 100, each having a tilted plate extending from itstop edge toward a central crossline of the opening of the exhaust duct40 to provide a pair of vent routes 23, on the left and right, both ofwhich head toward the corresponding half portions of the exhaust ductopening 40, wherein the drawer device 30 comprises a drive motor 31housed between the partitions 21, a pair of drive shafts 31 protrudingto the left and right substantially horizontally from the drive motor 31toward the corresponding vent routes 23 through the correspondingpartitions 21, and a pair of sirocco fans 33 respectively mounted on thedrive shafts 32 and respectively housed in the vent routes 23, theblades 33a of the sirocco fans 33 arranged to converge in overallconfiguration toward the drive motor 31.

As described in the above, the blades 33a of each sirocco fan 33 whichis driven by the drive motor 31 are arranged to converge toward thedrive motor 31, and the drawer device 30 is installed in the vent box 20which communicates with the exhaust duct 40 through the connectionenclosure 20a, the vent box 20 being either directly installed in therange hood 11 (FIG. 1), or installed in the housing box 10 which isarranged above the range hood 11 in fluid communication therewith (FIG.6). The vent routes 23 running between the side walls of the connectionenclosure 20a and the tilted plates 22 of the partitions 21 are directedtoward the respective halves of the exhaust duct opening 40.

The function of the exhaust device 100 of the present invention isdescribed in the following generally based on the movement of the air(fumed air) drawn up into the range hood 11.

First of all, a few advantages of the present invention are brieflyexplained. In FIG. 1, an exhaust device 100 is shown installed in arange hood 11 which is set up over a cooking range 210 of a systemkitchen 200. The overall design of the system kitchen 200 is notadversely affected by this arrangement. The overall design of the systemkitchen 200 will not be adversely affected either when the exhaustdevice 100 is housed in a housing box 10 installed above the range hood11 as shown in FIG. 6. In either setting, the direct installment in therange hood 11 or installation in the housing box 10 above the range hood11, no substantial change in design of the range hood 11 will benecessary. Even when a minor change is desired or required of the rangehood 11, the space needed for setting up the range hood 11 will remainsubstantially unchanged. The present invention with additionaladvantages can still provide a compact range hood 11 as well asstreamlined system kitchen 200.

Heated fumed air containing harmful gaseous substances and steam as wellas oil containing smoke is unavoidably produced from cooking on the gasrange 210 of the system kitchen 200. The fumed air goes up and isreceived by the range hood 11. The drawer device 30 of the exhaustdevice 100 promotes suction of the fumed air, which will be drawn intothe interior of the range hood 11 as indicated by the arrowed lines inFIGS. 2 and 3, and finally expelled into the open air through theexhaust duct 40.

As explained, the fumed air is forcibly sent into the exhaust duct 40 bythe drawer device 30. The function of the drawer device 30 is describedin detail in the following based on the flow courses of the sucked(fumed) air. The drive motor 31 of the drawer device 30 drives the driveshafts 32 as well as the sirocco fans 33 mounted thereon. The blades 33aof the sirocco fans 33 "cleave" or cut the air and expel the cleft (cut)air to the rear. The drawer device 30 is housed in the vent box 20having suction openings 24 on the right and left side walls and anexhaust opening 25 on the top. The air sucked into the range hood 11 isdrawn into the vent box 20 through the suction openings 24 with the workof the sirocco fans 33 and is expelled through the exhaust opening 25 asindicated by the arrowed lines in FIGS. 2 and 3.

It should be noted that the overall configuration of the blades 33a ofeach sirocco fan 33 is truncated conic converging toward the drive motor31 from the suction openings 24 of the vent box 20. Accordingly, it isto be understood that the flow speed or rate of the air sucked by theblades 33a is relatively low near the side walls of the vent box 20where the sirocco fans 33 are wider, and relatively high near thepartitions 21 where the sirocco fans 33 are narrower.

The foregoing pneumatic phenomenon of the air flow is further explainedin the following. The exhaust opening 25 connected with a range duct 40is made narrower than the main body portion of the vent box 20 as shownin FIG. 3. The "outer" air flow paths leading to the exhaust opening 25along the inner side walls of the vent box 20 from the suction openings24 are shorter than the "inner" air flow paths leading to the exhaustopening 25 via the partitions 21. According to the present invention,the flow rate of the air running along the inner air flow paths in thevent routes 23 is higher than the flow rate of the air running along theouter air flow paths in the vent routes 23, which provides a practicallyuniform flow rate anywhere in the vent routes 23 without fluctuation inair pressure or turbulence in the air flow. Thus, the overall air flowwithin the vent box 20 is satisfactorily smooth regardless of air flowroutes in the vent box 20.

Equally important is that the connection enclosure 20a which convergestoward the exhaust duct 40 is provided in an upper portion of the ventbox 20, and that the pair of partitions 21 each having a tilted plate 22are provided to form vent routes 23 in the vent box 20 which houses thedrive motor 31, the plates 22 being inclined toward a central crosslineof the exhaust duct opening 40. Those vent routes 23 are so configured,as shown in FIG. 3, as to naturally and reasonably conduct the fumed airsucked by the sirocco fans 33 toward the exhaust opening 25 from thesuction openings 24 provided on the side walls of the vent box 20.

The present invention eliminates virtually all obstructive factors fromthe vent box 20 which would otherwise interfere with air flow in thesystem; rather the present invention expedites the air flow from thesuction openings 24 toward the exhaust opening 25 by means of thesirocco fans 33 driven by the drive motor 31 of the drawer device 30,facilitating the drive motor 31 to function at its maximum capacitywithout generating unpleasant noise. The fact that two sirocco fans 33are utilized in a well balanced way, respectively mounted on the pair ofdrive shafts 32 which protrude generally horizontally to the right andleft from the drive motor 31 in the drawer device 30 further contributesto the reduction of noise.

The vent box 20 housing the drawer device 30 shown in FIGS. 1 and 2 isinstalled directly in the range hood 11. Here, the fumed air received bythe range hood 11 is sucked into the vent box 20 from its suctionopenings 24 (FIG. 2). On the other hand, the vent box 20 shown in FIG. 6is housed in a housing box 10, which is connected with the top of therange hood 11 in fluid communication. Here, the air received by therange hood 11 is first sucked into the housing box 10 as indicated bythe arrowed lines. Then the air is sent to the vent box 20 in fluidcommunication with the housing box 10 through the suction openings 24,the air eventually sent to the exhaust opening 25 connected with thebottom opening of the exhaust duct 40.

Either exhaust device 100 of the present invention is capable ofefficiently drawing fumed air produced around a cooking range into therange hood 11, and will not generate unpleasant noise while working,assisted by the fact that the exhaust device 100 substantiallyeliminates suction loss.

Either exhaust device 100 facilitates employment of an exhaust systemwith a capacity as high as "700 cubic meter/h" without generating muchnoise, therefore, a need for extra installation of an air supply systemin a kitchen is virtually eliminated. No substantial change is requiredin designing of range hoods 11 to secure more internal room forinstallation of an exhaust device 100.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view showing a portion of a system kitchen whichemploys an exhaust device according to an embodiment of the presentinvention.

FIG. 2 is a front view of the exhaust device as installed in a rangehood.

FIG. 3 is an enlarged front view showing a vent box according to thepresent invention as employed in the exhaust device.

FIG. 4 is an enlarged plan view showing in detail the vent box and adrawer device housed in the vent box according to the present invention.

FIG. 5 is a side elevational view showing the drawer device in detail.

FIG. 6 is front view of an exhaust device according to anotherembodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In FIG. 1, there is shown an exhaust device 100 according to anembodiment of the present invention as installed in a system kitchen200. The system kitchen 200 includes a gas cooking range 210 over whichis provided a range hood 11.

The range hood 11 houses a vent box 20, a feature of an exhaust device100 of the present invention. Connected to the vent box 20 in fluidcommunication is an exhaust duct 40. In another embodiment of thepresent invention shown in FIG. 6, this vent box 20 is installed in ahousing box 10 instead of the range hood 11 which is installed above therange hood 11, the housing box 10 enclosing a bottom portion of theexhaust duct 40 which is in fluid communication with the vent box 20.

The vent box 20 having suction openings 24 on the right and left sidewalls includes in an upper portion thereof a connection enclosure 20a asshown in FIGS. 2-4. The connection enclosure 20a has an exhaust opening25 which opens to the bottom opening of the exhaust duct 40. In the ventbox 20 are also provided a pair of generally vertical partitions 21 eachwith a tilted plate 22 as shown in FIGS. 3 and 4 to form practicallyidentical vent routes 23 on their left and right.

In the foregoing another embodiment shown in FIG. 6, where the vent box20 including the connection enclosure 20a is housed within a vent space12 in the housing box 10, the exhaust opening 25 being in fluidcommunication with the bottom opening of the exhaust duct 40.

The partitions 21 with the tilted plates 22 provide a pair of ventroutes 23 on their right and left respectively as explained, andtogether support a drive motor 31 of a drawer device 30 which isinstalled in the central axial portion of the vent box 20. Each tiltedplate 22 extends in an orientation toward a central crossline of theopening of the exhaust duct 40 such that the fumed air sucked into thecorresponding vent route 23 is naturally and reasonably directed towardthe corresponding half of the exhaust duct opening 40 in cooperationwith the corresponding tilted side wall of the connection enclosure 20a.The drive shafts 32 of the drive motor 31 of the drawer device 30protrude to the left and right practically horizontally through thepartitions 21 into the vent routes 23 as shown in FIG. 4.

The drawer device 30 has the drive motor 31 and a pair of sirocco fans33 mounted on the drive shafts 32 of the drive motor 31 correspondingly.Each sirocco fan 33 is housed in the corresponding vent route 23. Eachsirocco fan 33 has a number of blades 33a, the overall configuration ofthe blades 33a is a truncated cone converging from the correspondingsuction openings 24 of the vent box 20 toward the drive motor 31, whicheffectively assists the air sucked by the sirocco fan 33 to smoothlyflow into the corresponding vent route 23 without causing turbulence.

In the foregoing embodiments, the suction openings 24 are provided onthe right and left side walls of the vent box 20, and the exhaustopening 25 connected with the exhaust duct 40 in fluid communication isprovided on the top of the vent box 20, the remaining elements of thepresent invention being installed in position accordingly. However, itshould be understood that various modifications and changes can be madeto those embodiments, such as providing the drive shafts 32 of the drivemotor 31 to protrude backward and forward within the vent box 20, orconnecting the exhaust duct 40 to a side wall of the vent box 20.

Attachment

Reference for the numerals in the figures

100 exhaust device

10 housing box

11 range hood

12 vent space

20 vent box

21 partitions

22 tilted plate

23 vent routes

24 suction openings

25 exhaust opening

30 drawer device

31 drive motor

32 drive shafts

33 sirocco fans

33a blades

40 exhaust duct

200 system kitchen

210 gas range

The present invention having been described, what is claimed is:
 1. Anexhaust device (100) to draw in fumed air produced from cooking on acooking range (210) in a kitchen and to expel said fumed air into anexhaust duct (40), comprising:a vent box (20) connected with saidexhaust duct (40) in fluid communication therewith, which is installedin one of a range hood (11) and in a housing box (10) connected with arange hood (11) in fluid communication therewith; and a drawer device(30) housed in said vent box (20), wherein said vent box (20) includes aconnection enclosure (20a) in an upper portion thereof in fluidcommunication with said exhaust duct (40) which converges toward saidexhaust duct (40), wherein a pair of substantially vertical partitions(21) are provided within said vent box (20) on opposite sides from alongitudinal axis of said vent box (20), each having a tilted plate (22)extending toward a central crossline of an opening of said exhaust duct(40), to provide a pair of vent routes (23) together with side walls ofsaid vent box (20), said vent routes (23) converging toward said exhaustduct (40), wherein said drawer device (30) comprises: a drive motor(31); a pair of drive shafts (32) protruding substantially horizontallyin opposite directions from said drive motor (31) correspondingly intosaid vent routes (23) through said partitions (21); and a pair ofsirocco fans (33) having blades (33a) correspondingly mounted on saiddrive shafts (32) in said vent routes (23), each set of said blades(33a) converging toward said drive motor (31).
 2. An exhaust device asclaimed in claim 1 wherein said motor is housed between twosubstantially vertical partitions extending in parallel to a centerlineof said device, said partitions further including two angled platesextending from top edges of said partitions toward each other to meet atthe centerline of the device.
 3. An exhaust device as claimed in claim 2wherein said vent box is larger than said exhaust duct.
 4. An exhaustdevice as claimed in claim 3 wherein an angle of the pyramid transitionmember is equal to the angled plates atop the partitions.
 5. An exhaustdevice as claimed in claim 1 wherein said device includes intakeopenings in said side walls of said vent box.
 6. An exhaust device asclaimed in claim 1 wherein said vent box includes an exhaust openinghaving a smaller dimension than said vent box.
 7. An exhaust devicecomprising:a hood; a vent box in fluid connection with said hood; anexhaust duct in fluid connection with said vent box; a drawer devicehoused within said vent box, said drawer device including:a motorlocated centrally in said device; two drive shafts extending from anddriven by said motor; two truncated conical fans, located in dividedflow routes, one mounted to each drive shaft, said fans being orientedsuch that said truncated conical shape converges toward said motor; saidfans moving exhaust gas more quickly proximal to said motor and over alonger flow path and more slowly distal from said motor along a shorterflow path, said exhaust thereby maintaining a substantially equal speedalong the longer and shorter paths, avoiding turbulence.
 8. An exhaustdevice as claimed in claim 7 wherein said truncated conical fans aresirocco fans.
 9. An exhaust device as claimed in claim 7 wherein saidpartitions divide said device into the two flow routes which aresubstantially similar and unobstructed.
 10. An exhaust device as claimedin claim 7 wherein said two truncated fans are identical to each other.11. An exhaust device to draw exhaust gasses from a cooking hood over acooking apparatus and expel said gasses to a selected locationcomprising:a bifurcated vent box in fluid communication with saidcooking hood and said selected location; at least one drive motorassociated with said vent box; two truncated conical fans each driven bysaid at least one motor, said truncated conical fans being adapted toaccelerate exhaust gasses to differing degrees over the conical shape toaccelerate gasses traveling over a longer flow path to a higher degreeand accelerate gasses traveling over a shorter flow path to a lesserdegree such that turbulence is avoided in said gasses.